udev: downgrade message when we fail to set inotify watch up

udev: downgrade message when we fail to set inotify watch up

My logs are full of:

systemd-udevd[6586]: seq 13515 queued, 'add' 'block'
systemd-udevd[6586]: seq 13516 queued, 'change' 'block'
systemd-udevd[6586]: seq 13517 queued, 'change' 'block'
systemd-udevd[6586]: seq 13518 queued, 'remove' 'bdi'
systemd-udevd[6586]: seq 13519 queued, 'remove' 'block'
systemd-udevd[9865]: seq 13514 processed
systemd-udevd[9865]: seq 13515 running
systemd-udevd[9865]: GROUP 6 /usr/lib/udev/rules.d/50-udev-default.rules:59
systemd-udevd[9865]: IMPORT builtin 'blkid' /usr/lib/udev/rules.d/60-persistent-storage.rules:95
systemd-udevd[9865]: IMPORT builtin 'blkid' fails: No such file or directory
systemd-udevd[9865]: loop4: Failed to add device '/dev/loop4' to watch: No such file or directory
(the last line is at error level).
If we are too slow to set up a watch and the device is already gone by the time
we try, this is not an error.